Core sample orientation

ABSTRACT

A core orientation device ( 10 ) for a core drill ( 12 ). The device ( 10 ) comprises an arrangement ( 14 ) for providing signals ( 16 ) associated with a physical orientation ( 18 ) of the core orientation device ( 10 ). Processing means ( 22 ) are provided for processing the signals ( 16 ) so as to provide processed data ( 23 ) from which a measure ( 24 ) of the physical orientation ( 18 ) of the core orientation device ( 10 ) can be established. The measure ( 24 ) is associated with the physical orientation ( 18 ) of the device ( 10 ) at a particular moment in time. A memory ( 26 ) is coupled to the processing means  22  for storing the processed data  23 . To this end there is provided an interface means ( 27 ) comprising first means ( 28 ) for storing the processed data ( 23 ) in the memory ( 26 ) and second means ( 30 ) for accessing the memory ( 26 ) to provide the measure ( 24 ) of the physical orientation ( 18 ) of core orientation device ( 10 ) when required.

This application is a Continuation of U.S. Ser. No. 13/632,697 filed 1Oct. 2012, which is a Continuation of U.S. Ser. No. 13/250,551, filed 30Sep. 2011, which is a Continuation of U.S. Ser. No. 12/980,686, filed 29Sep. 2010, which is a Continuation of U.S. Ser. No. 12/551,890, filed 1Sep. 2009, which is a Continuation of U.S. Ser. No. 10/594,355, filed 5Jul. 2007, now U.S. Pat. No. 7,584,055, issued 1 Sep. 2009, which is aNational Stage Application of PCT/AU2005/001344, filed 5 Sep. 2005,which claims benefit of Serial No. 2004905021, filed 3 Sep. 2004 inAustralia and which applications are incorporated herein by reference.To the extent appropriate, a claim of priority is made to each of theabove disclosed applications.

FIELD OF THE INVENTION

This invention relates to core sample orientation. More particularly,the invention relates to an orientation device for providing anindication of the orientation of a core sample relative to a body ofmaterial from which the core has been extracted, and also to a method ofcore sample orientation identification.

BACKGROUND ART

There is a need for core sampling in geological surveying operations.

Core samples are obtained through core drilling operations. Coredrilling is typically conducted with a core drill comprising outer andinner tube assemblies. A cutting head is attached to the outer tubeassembly, so that rotational torque applied to the outer tube assemblyis transmitted to the cutting head. A core is generated during thedrilling operation, with the core progressively extending along theinner tube assembly as drilling progresses. When a core sample isacquired, the core within the inner tube assembly is fractured. Theinner tube assembly and the fractured core sample contained therein, arethen retrieved from within the drill hole, typically by way of aretrieval cable lowered down the drill hole. Once the inner tubeassembly has been brought to ground surface, the core sample can beremoved and subjected to the necessary analysis.

Typically, the core drilling operation is performed at an angle to thevertical, and it is desirable for analysis purposes to have anindication of the orientation of the core sample relative to the groundfrom which it was extracted. It is therefore important that there besome means of identifying the orientation the core sample had within theground prior to it having been brought to the surface.

Core orientation devices are used to provide an indication of theorientation of the core sample.

One common way of obtaining an indication of the orientation of a coresample is through use of an orientation spear comprising a marker (suchas a crayon) projecting from one end of a thin steel shank, the otherend of which is attached to a wire line.

The orientation spear is lowered down the drill hole, prior to the innertube assembly being introduced. The marker on the orientation spearstrikes the facing surface of material from which the core is to begenerated, leaving a mark thereon. Because of gravity, the mark is onthe lower side of the drill hole. The inner tube assembly is thenintroduced into the outer tube assembly in the drill hole. As drillingproceeds, a core sample is generated within the inner tube assembly. Thecore sample so generated carries the mark which was previously applied.Upon completion of the core drilling run and retrieval of the coresample, the mark provides an indication of the orientation of the coresample at the time it was in the ground.

There are also mechanical core orientation devices for marking a coresample prior to its extraction from the drill hole. Typically,mechanical devices are adapted to be incorporated in the inner tubeassembly for marking the core. An example of such a mechanicalorientation device is disclosed in WO 03/038212.

It is against this background and the problems and difficultiesassociated therewith that the present invention has been developed.

DISCLOSURE OF THE INVENTION

According to a first aspect of the invention there is provided a coreorientation device for a core drill, the device comprising: anarrangement for providing signals associated with a physical orientationof the core orientation device; processing means for processing thesignals provided by the arrangement so as to provide processed data fromwhich a measure of the physical orientation of the core orientationdevice can be established, the measure being associated with thephysical orientation of the device at a particular moment in time;memory for storing the processed data; and interface means having firstmeans for storing the processed data in the memory and second means foraccessing the memory to provide the measure of the physical orientationof core orientation device when required.

Most preferably the physical orientation of the core orientation devicecomprises a rotational orientation about an axis thereof. In thesearrangements the rotational orientation is preferably about alongitudinal axis of the core orientation device. In other arrangementsthe physical orientation does not comprise a rotational orientation butrather comprises an angular orientation of the longitudinal axis aboveor below the horizontal plane. Embodiments may be proved where more thanone orientation is measured. For example the physical orientation of thecore orientation device may include both a rotational orientation abouta longitudinal axis of the core orientation device and an angularorientation of the longitudinal axis above or below the horizontalplane.

Preferably the arrangement comprises triaxial accelerometer means. Inthese embodiments the triaxial accelerometer means may be advantageouslyhoused by cushioning. The cushioning may increase in robustnessoutwardly. The cushioning may include an outer cushioning layer, anintermediate cushioning layer, and an inner cushioning layer whichembraces the triaxial accelerometer means, with the robustness ofcushioning progressively decreasing from the outer layer to the innerlayer.

The triaxial accelerometer means may comprise three accelerometersarranged to determine acceleration in three orthogonal directions.

Preferably the core orientation device includes means for relating themeasure of the orientation of the core orientation device with thepresent orientation thereof such that the core orientation device can berotated to reflect the measure of the orientation of the coreorientation device.

Preferably the core orientation device includes means for inputting theparticular moment in time into the processing means and means forsubsequently displaying the measure of the physical orientation of thedevice, the measure being associated with the physical orientation ofthe device at the inputted moment in time.

Preferably the core orientation device has a body in the form of ahousing having at least one threaded end for being engaged by an innertube assembly of a core drill so as to form a part thereof. When engagedby the inner tube assembly the core orientation device preferably formsa length of the inner tube assembly.

Preferably the processing means includes a timer configured for ensuringthat the processing means processes signals from the arrangement overpredetermined time intervals.

Preferably the processor means includes integration means forintegrating signals from the arrangement over a predetermined timeinterval.

Preferably the core orientation device includes means for displaying thecommencement of a reference time.

According to a second aspect of the invention there is provided a coredrill having a core orientation device comprising: an arrangement forproviding signals associated with a rotational orientation of the coreorientation device; processing means for processing the signals providedby the arrangement so as to provide processed data from which a measureof the rotational orientation of the core orientation device can beestablished, the measure being associated with the rotationalorientation of the device at a particular moment in time; memory forstoring the processed data; and interface means having first means forstoring the processed data in the memory and second means for accessingthe memory to provide the measure of the rotational orientation of coreorientation device when required; wherein the core drill comprises:means for maintaining knowledge of the relative rotational orientationof a core drilled by the core drill and the core orientation device suchthat a measure of the rotational orientation of the core can beestablished using the measure of the rotational orientation of the coreorientation device.

Preferably the means for maintaining knowledge of the relativerotational orientation of the core drilled by the core drill comprises amechanism for preventing rotational movement about the length of thecore sample, relative to the core orientation device.

Preferably the core orientation device includes means for relating themeasure of the orientation of the core orientation device with thepresent orientation thereof such that the core orientation device can berotated to reflect the measure of the orientation of the coreorientation device.

Preferably the core drill includes an outer tube assembly and an innertube assembly with the inner tube assembly having a means foraccommodating the core orientation device along the length of the innertube assembly. Preferably inner tube assembly includes a bearingallowing the means for accommodating the core orientation device torotate relative to the outer tuber assembly but not relative to the coresample when the core is received by the inner tube assembly.

Preferably the outer tube assembly includes a spacer for allowing theinner tube assembly to be fitted with the outer tube assembly, when thecore orientation device is accommodated. The core drill may accordinglycomprise a retrofitted core drill.

Preferably the core orientation device is cylindrical and one end of thecore orientation device includes display and input means. The displaymeans preferably comprises and LCD display and the input preferablycomprises a keypad. Most advantageously the end of the core orientationdevice is preferably protected by the inner tube assembly whenaccommodated.

According to a third aspect of the invention there is provided a methodof obtaining and orientating a core sample comprising:

-   -   moving a core drill having a core orientation device from a        first location to a drilling location and thereafter operating        the core drill to drill a core sample;    -   generating signals associated with a physical orientation of the        core orientation device between the first location and the        drilling location;    -   processing the signals to provide processed data from which a        measure of orientation of the core orientation device at the        drilling location can be established;        and    -   storing the processed data in memory such that the measure of        the physical orientation of the core orientation device can be        obtained therefrom.

Preferably the method includes maintaining knowledge of the relativephysical orientation of the core orientation device and the core sampleafter the core sample has been drilled such that a measure of theorientation of the core sample taken by the core drill can be providedusing the measure of the orientation of the core orientation device,when at a location spaced from the drilling location.

Preferably the method includes initialising the orientation of the coreorientation device at the first location, said initialising beingperformed by commencing said generating and processing the signals atthe first location with the core orientation device in a knownorientation.

Preferably the location spaced from the drilling location is the firstlocation and the measure of the orientation of the core orientationdevice is provided by maintaining the same relative orientation of thecore orientation device and core sample after the core sample has beentaken.

Preferably the method includes displaying a related measure of theorientation of the device and varying that measure upon rotation of thecore sample and device such that a user can position the core sample anddevice in the measured orientation for marking.

In preferred embodiments of the invention the arrangement comprisesthree accelerometers operating on respective axes. The signals providedby the arrangement accordingly comprise acceleration signals which areassociated with the physical orientation of the core orientation device.In these embodiments the processing means preferably processes thesignals to provide data representative of the change in orientation ofthe core orientation device over a plurality of predetermined timeintervals. The interface means operates to store the changes inorientation in the memory.

By keeping track of the time taken to move the core drill to a coresample site and commence drilling, which may occur several kilometresbelow sea level, the operator, is preferably able to readily access thememory of the device, one raised to the surface, to provide a measure ofthe orientation of the core orientation device when aligned with thecore sample, and thus thereby obtain a measure of the orientation of thecore sample.

Dip in exploration drilling is an important measure in the geologicalanalysis of core samples. Often dip is measured in degrees above orbelow the horizontal plane. Preferably the processing means processesthe signals provided by the arrangement to provide processed data fromwhich a measure of the orientation of the core orientation devicerelative to the horizontal plane can be established. Rotationalorientation is also an important measure.

Preferably the processing means includes an analog to digital converterfor converting the signals provided by the accelerometers.

Preferably core orientation device include a body that is adapted to becoupled to a tubular core drill for drilling the core sample. In thesearrangements the processed data stored in the memory is preferablyderived from signals associated with movement of the body of the coreorientation device.

The processing means preferably includes timer means for determiningpredetermined intervals relative to a reference time, and means forstoring the processed data in the memory upon each of the predeterminedintervals terminating. Preferably the processor means includesmathematical integration means for use in processing the signals fromthe arrangement.

Preferably the core orientation device includes means for inputting aselected time interval and means for relating the selected time intervalto at least a portion of the processed data stored in the memory.Preferably the core orientation device includes means for using theportion of processed data to establish the measure of the orientation ofthe device, and means for displaying the measure to a user.

According to another aspect of the invention there is provided anorientation device for providing an indication of the orientation of acore sample relative to a body of material from which the core has beenextracted, the orientation device comprising means for determining andstoring the orientation of the device at predetermined time intervalsrelative to a reference time, means for inputting a selected timeinterval, means for relating the selected time interval to one of thepredetermined time intervals and providing an indication of theorientation of the device at the selected time interval.

Such an orientation device is typically attached to an inner tubeassembly of a core drill and is fixed against rotation relative thereto.For this purpose, the orientation device according to the inventionpreferably includes means for attachment to the inner tube assembly.

Preferably, the orientation device further includes means for comparingthe orientation of the device at the selected time interval to theorientation of the device at any subsequent time and providing anindication of the direction in which the device should be rotated inorder to bring it into an orientation corresponding to the orientationof the device at the selected time.

According to another aspect of the invention there is provided anorientation device for providing an indication of the orientation of acore sample relative to a body of material from which the core samplehas been extracted, the orientation device comprising means forgenerating signals responsive to the orientation of the device, aprocessor for receiving the generated signals and for processing thesignals to generate orientation data representative of the orientationof the device, means for storing the orientation data at predeterminedtime intervals, means for inputting a signal representative of aselected time interval to the processor, the processor operating torelate the selected time interval to the predetermined time intervalsand output a signal indicative of the orientation of the device at theselected time interval.

Preferably, further data is generated representative of the orientationof the device at any subsequent time and the processor is operable tooutput a signal to a display means to provide a visual indication of thedirection in which the device should be rotated at said subsequent timein order to bring the device into an orientation corresponding to itsorientation at the selected time.

According to yet another aspect of the invention there is provided acore drill comprising an inner tube assembly and an orientation deviceaccording to any one of the above aspects of the invention.

According to yet another aspect of the invention there is provided acore drill comprising an inner tube assembly and an orientation deviceaccording to the second aspect of the invention.

According to yet another aspect of the invention there is provided amethod of providing an indication of the orientation of a core samplerelative to a body of material from which the core sample has beenextracted, the method comprising: drilling a core sample from a body ofmaterial with a core drill having an inner tube assembly; recording theorientation of the inner tube at predetermined time intervals withreference to an initial reference time during said drilling; recordingthe specific time interval beyond the reference time at which the coresample was separated from the body of material; removing the inner tubeassembly and core sample contained therein from the body of material;and relating the recorded specific time to the recorded time intervalsto obtain an indication of the orientation of the inner tube andconsequently the core contained therein at the specific time interval.

Preferably, the method according to the invention is performed using anorientation device attached to the inner tube assembly, the orientationdevice being in accordance with an aspect of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will be better understood by reference to the followingdescription of one specific embodiment thereof as shown in theaccompanying drawings in which:

FIG. 1 is a schematic view of a core drill with an orientation deviceaccording to the embodiment;

FIG. 2 is a schematic side elevational view of the arrangement shown inFIG. 1;

FIG. 3 is a further schematic side elevational view of a lower part ofthe arrangement shown in FIG. 2;

FIG. 4 is a schematic side elevational view in section of theorientation device;

FIG. 5 is a block diagram illustrating various components of theorientation device; and

FIG. 6 is a schematic plan view of a keypad and display provided at oneend of the orientation device.

BEST MODE(S) FOR CARRYING OUT THE INVENTION

Referring to FIG. 1 there is shown a core orientation device 10 for acore drill 12. The device 10 comprises an arrangement 14 for providingsignals 16 associated with a physical orientation of the coreorientation device 10. According to the embodiment the physicalorientation of the core orientation device 10 comprises rotationalorientation 18 about a longitudinal axis 20 of the core orientationdevice 10.

The core orientation device 10 includes processing means 22 forprocessing the signals 16 provided by the arrangement 14 so as toprovide processed data 23 from which a measure 24 of the rotationalorientation 18 of the core orientation device 10 can be established. Themeasure 24 is associated with the rotational orientation 18 of thedevice 10 at a particular moment in time.

A memory 26 is coupled to the processing means 22 for storing theprocessed data 23. To this end there is provided an interface means 27comprising first means 28 for storing the processed data 23 processed bythe processing means 22 in the memory 26 and second means 30 foraccessing the memory 26 to provide the measure 24 of the rotationalorientation 18 of core orientation device 10. This allows the measure 24to be obtained when required.

As shown in FIG. 2 the core drill 12 comprises an outer tube assembly 34and an inner tube assembly 36 of generally conventional construction.

The orientation device 10 according to the embodiment is accommodatedalong the length 38 of the inner tube assembly 36, as shown in FIG. 2 ofthe drawings. In this arrangement the inner tube assembly 36 comprisesupper and lower parts 36 a, 36 b between which the orientation device 10is fitted. The upper part 36 a includes a bearing 40, with the portionabove the bearing 40 being rotatable with the outer tube assembly 34 andthe portion below the bearing 40 being restrained against rotationbecause of frictional engagement with the core being generated. Thus, inthis manner the bearing 40 allows the core orientation device 10 torotate relative to the outer tube assembly 34 but not relative to thecore sample when the core is received.

Incorporating the orientation device 10 in the inner tube assembly 36increases the overall length of the inner tube assembly 36, aconsequence of which is that the overall length of the outer tubeassembly 34 needs to also be increased. A spacer 42 is provided in theouter tube assembly 34 for this purpose. Apart from modifications to theinner tube assembly 36 to accommodate the orientation tool 10, and alsothe spacer 42 provided in the outer tube assembly 36, the core drill 12is of conventional construction and operates in a conventional way.

Referring to FIG. 3 it can be seen that the inner tube assembly 36comprises a back end assembly 33, a replacement grease sub 35, the coreorientation device 10, 3 m of inner tube 37 and core lifter case 39.

As shown in FIG. 4, the orientation device 10 comprises a housing 44 ofgenerally cylindrical construction thereby defining the centrallongitudinal axis 20. The housing 44 has a generally cylindrical sidewall 46 and two opposed ends 48, 50. The end 48 is open and internallythreaded to provide a female threaded formation (not shown). A malethreaded formation 52 is provided on the cylindrical side 46 of thehousing 40 inwardly spaced from the other end 50.

The female threaded formation (not shown) and the male threadedformation 52 are provided so that the orientation device 10 can beinstalled between, and in threaded engagement with, the upper and lowerparts 36 a, 36 b of the inner tube assembly 36, as shown in FIG. 2. Theinner tube assembly 36 accordingly has complementary threaded portions(not shown) which provide means for accommodating the core orientationdevice 10 along the length of the inner tube assembly 36.

The housing 44 accommodates an internal chassis 54.

The chassis 54 has a cavity 56 which accommodates shock absorbingmaterial 57 encasing a triaxial accelerometer means 58.

The shock absorbing material 57 comprises several layers of cushioning.Specifically, there is an outer cushioning layer, an intermediatecushioning layer, and an inner cushioning layer which embraces thetriaxial accelerometer means 58, with the robustness of cushioningprogressively decreasing from the outer layer to the inner layer.

As shown in FIG. 5, the housing 44 also accommodates a main printedcircuit board 60 and an electrical power source 62 in the form of alithium battery pack. The processing means 22 comprises an electroniccircuit with chip on the main printed circuit board 60. The processingmeans 22 incorporates an analogue-to-digital converter 64, a low-powermicrocontroller 66 which provides a processor, a timer 68 andnon-volatile memory 70, as illustrated schematically in FIG. 6. Thus inthis embodiment the memory 26 forms part of the processing means 22.

The interface means 27 forms part of the processing means 22 whilehaving the first means 28 for storing the processed data 23 and secondmeans 30 for accessing the memory 26 to provide the measure 24 of therotational orientation 18 of core orientation device 10 at theassociated time. A watchdog circuit 71 is provided for watching thesystem. In instances where the device 10 shuts down downhole it can bereset at the surface.

The triaxial accelerometer means 58 comprises three internal siliconaccelerometers operating along orthogonal directions X, Y and Z. Thethree accelerometers measure components of the earth's gravitationalfield.

Mathematically transforming the outputs from the three accelerometersallows the rotational orientation 18 of the device 10 about itslongitudinal axis 20 to be determined.

More particularly, the signals 16 produced by the triaxial accelerometermeans 43 are determinative of the change in orientation of the device 10and are transmitted to the analogue-to-digital converter 64 which inturn transmits signals or signal data, to the microcontroller 66.

The timer 68 is provided for ensuring that the processing meansprocesses signals from the arrangement over predetermined timeintervals. In this arrangement the processor means 22 includesintegration means for integrating signals over a particularpredetermined time interval of 1 minute.

When orientation device 10 is operating, the relative orientation of thedevice is determined at regular intervals as determined by processingmeans 22. The processing means 22 employs the interface means 27 andsecond means 30 to store the processed data 23 in memory 26. In thisembodiment, the time intervals at which the orientation is determinedand stored comprises intervals of one minute. In this way, there is astored record of the orientation of the device 10 at minute intervals.The orientation of the orientation device 10 of course corresponds tothe orientation of the lower part 36 b of the inner tube assembly 36which in turn corresponds to the orientation of a core sampleprogressively entering the inner tube assembly 36, as the lower part 36b does not rotate relative to the core sample.

The following process occurs in the operation of the core orientationdevice 10 and the core drill 12. A first step comprises moving the coredrill 12 having the core orientation device 12 forming part thereof froma first location to a drilling location. After this the core drill 12 isoperated to drill a core sample.

While the core drill is moved from the first location to the drillinglocation the core orientation device 10 generates acceleration signals16 associated with the rotational orientation 18 of a core orientationdevice 10. The processing means 22 then processes the signals 16 toprovide processed data 23 from which the measure 24 of rotationalorientation 18 of the device 10 at the drilling location can beestablished. The processed data 23 is stored in memory 26 for laterrecall such that the measure 23 of the rotational orientation 18 of thedevice 10 can be obtained therefrom.

By using integration means and time intervals of one minute theprocessed data 23 is indicative of the change orientation of the device10 in one minute intervals commencing from a reference time thatcorresponds to the time at which the orientation device 10 was started.

As shown in FIG. 6, the core orientation device includes a membranekeypad 72 and an LCD display 74, both of which are provided at end 50 ofthe orientation device 10. With this arrangement, the keypad 72 isaccessible for operation from the end 50 and the display 74 is alsovisible from that end, but of course only when the orientation device 10is not connected to upper part 36 a of the inner tube assembly 36. Thekeypad 72 incorporates a window section 76 through which the LCD display74 is visible. The keypad 72 has four keys in this embodiment,identified in FIG. 4 as “N”, “R”, “+” and “−” keys.

As will be appreciated the membrane keypad 72 and 74 are protected bythe inner tube assembly 36 when accommodated in the female threadedportion (not shown).

In this embodiment, the orientation device 10 is started by pressing the“N” key on the keypad 72. It is also necessary to record the timeduration between starting the core orientation device 10 and extractingthe core sample. Typically this is achieved by starting an external stopwatch at the time of starting of the orientation device 10. Otherarrangements are of course possible.

The stop watch is started at the time that the orientation device 10displays a signal on the display 31 indicating that operation of theorientation device 10 has started. This provides for added accuracy.

Once the orientation device 10 has been started and recording of thesubsequent time duration commenced, the inner tube assembly 36 isinserted into a drill hole for reception in the outer tube assembly 13,and the core drilling operation commenced. During the drillingoperation, a core is progressively generated within the inner tubeassembly, as previous explained.

When the core is to be extracted, the core drill operator refers to thetimer and notes the time duration involved. Specifically, the operatoreither notes the full minute that has previously elapsed or waits untilthe next full minute elapses, and then records that time (as it must berecalled later). The operator then initiates the procedure for breakingthe core from the body of material, ensuring that no rotation of theinner tube assembly 36 occurs. The inner tube assembly 36 is retrievedfrom the drill hole in the conventional manner.

At the surface, the upper part 36 a of the inner tube assembly 36 isunscrewed from the orientation device 10, so as to the expose the end 50thereof to provide access to the keypad 72 and display 74. As previouslydescribed the frictional engagement of the core and the inner tubeassembly 36 b along with bearing 40 allows the lower part 36 b to rotaterelative to the outer tube assembly 34 but not relative to the coresample.

As will be described the device 10 includes means 80 for relating themeasure of the orientation of the core orientation device 10 with thecurrent rotational orientation thereof. This allows for the coreorientation device to consequently be rotated to reflect the measure ofthe orientation of the core orientation device. In this embodiment thisis achieved by inputting the time duration as measured by the externalstop watch into the orientation device 10 through the keypad 72. This isdone by pressing the “R” key to display numbers “00”, and then pressingthe .+/−. keys to display the relevant time duration in minutes.

Once the time has been entered, the key “R” is pressed once. This causesthe means 80 for relating the core orientation device to the currentrotational orientation thereof, to determine a current rotationalorientation 81 from processing means 22 and display a graphicalindication 83 of the direction in which the orientation device 10 andthe lower part 36 b of the inner tube assembly 36 attached theretoshould be rotated. Rotating the device and lower part 36 b in thisdirection causes the core contained within the inner tube assembly 36 bto move into an orientation corresponding to its orientation at the timethat it was in the ground before extraction. At this time a symbol 85 isdisplayed to alert the operator.

Once the required orientation has been established, the core samplewithin the inner tube assembly 36 can be marked as necessary. Afterremoval of the core sample from the lower part 36 b of the inner tubeassembly 36, the upper part 36 a can be fitted onto the orientationdevice 10 and the inner tube assembly 36 used for the next core sampledrilling stage.

The process by which the orientation device 10 determines and provides agraphical indication of the direction in which it should be rotated,together with the lower part 15 b of the inner tube assembly 36 attachedthereto, in order to be at an orientation corresponding to theorientation of the core sample in its original position within theground, operates on the following basis. The time measurement measuredby the operator and entered into the keypad 72 represents the durationof time between starting the orientation device 10 and the point atwhich the particular drilling process was terminated in order tofracture the core sample from the body of material to which it isattached so that the core sample could be retrieved from the drill holeand brought to surface level.

As previously explained, the orientation of the orientation device 10 isdetermined at predetermined intervals, which are minute intervals inthis embodiment. The timer simply allows identification of theparticular minute interval at which the appropriate orientation readingwas taken and recorded.

Inputting the time measurement into the keypad 72 allows the controller66 to compare the inputted reading to the various stored readings andidentify the relevant orientation reading. The triaxial accelerometermeans 58 provides signals responsive to the orientation of theorientation device 10 at any instant in time, including when operatingat surface level. Such signals allow the controller 66 to process thesignals and determine the orientation of the device at any instant. Thecontroller 53 can compare the instant of the device at surface level atany instant in time to the particular recorded reading corresponding tothe orientation of the device at the time that the core sample wasseparated from the body of material to which it was previously attached.This comparison is processed to provide data which is outputted to thedisplay 74 to provide a visual indication of the direction in which theorientation device should be rotated, as previously explained.

In this embodiment, the visual indication comprises a directional arrowarrangement showing the required rotational direction. Once theorientation device 10 is at the required orientation, the display 74provides an image 85 representing that condition.

From the forgoing, it is evident that the present invention provides anorientation device which does not require physical marking of a coresample prior to extraction thereof from the ground. Indeed, theorientation device according to the embodiment is particularlyconvenient for an operator to use. All that is required is for theoperator to start the orientation device prior to the inner tubeassembly 36 being inserted into the drill hole, and contemporaneouslystart a timer for recording the time duration before the drillingoperation ceases to allow the generated core sample to be retrieved.

Modifications and improvements may be made without departing from thescope of the invention. For example in other embodiment the physicalorientation does not comprise a rotational orientation but rather ameasure of degrees above or below the horizontal plane.

Throughout the specification, unless the context requires otherwise, theword “comprise” or variations such as “comprises” or “comprising”, willbe understood to imply the inclusion of a stated integer or group ofintegers but not the exclusion of any other integer or group ofintegers.

The claims defining the invention are as follows:
 1. A core orientationdevice for a core drill, the device comprising: an arrangement forproviding signals associated with a physical orientation of the coreorientation device; processing means for processing the signals providedby the arrangement so as to provide processed data from which a measureof the physical orientation of the core orientation device can beestablished, the measure being associated with the physical orientationof the device at a particular moment in time; memory for storing theprocessed data; and interface means having first means for storing theprocessed data in the memory and second means for accessing the memoryto provide the measure of the physical orientation of core orientationdevice when required.
 2. A core orientation device as claimed in claim 1wherein the physical orientation of the core orientation devicecomprises a rotational orientation about a longitudinal axis of the coreorientation device.
 3. A core orientation device as claimed in claim 1the physical orientation of the core orientation device comprises anangular orientation of the longitudinal axis above or below thehorizontal plane.
 4. A core orientation device as claimed in claim 1,wherein the arrangement for providing signals comprises triaxialaccelerometer means.
 5. A core orientation device as claimed in claim 1,wherein the core orientation device includes means for relating themeasure of the orientation of the core orientation device with thepresent orientation thereof such that the core orientation device can berotated to reflect the measure of the orientation of the coreorientation device.
 6. A core orientation device as claimed in claim 1wherein the core orientation device includes input means for inputtingthe particular moment in time into the processing means and displaymeans for subsequently displaying the measure of the physicalorientation of the device, the measure being associated with theinputted moment in time.
 7. A core orientation device as claimed inclaim 6 wherein the core orientation device is cylindrical and one endof the core orientation device includes the display and input means inthe form of a LCD display and keypad.
 8. A core orientation device asclaimed in claim 1 wherein the core orientation device has a body in theform of a housing having at least one threaded end for being engaged byan inner tube assembly of the core drill.
 9. A core orientation deviceas claimed in claim 8 wherein, when engaged by the inner tub assembly,the core orientation device forms a length of the inner tube assembly.10. A core orientation device as claimed in claim 1 wherein theprocessing means includes a timer configured for ensuring that theprocessing means processes signals from the arrangement overpredetermined time intervals.
 11. A core orientation device as claimedin claim 1, wherein the processor means includes integration means forintegrating signals from the arrangement over a predetermined timeinterval.
 12. A core orientation device as claimed in claim 1, whereinthe processor means includes timer means for determining predeterminedintervals relative to a reference time, and means for storing theprocessed data in the memory upon each of the predetermined intervalsterminating.
 13. A core drill having a core orientation devicecomprising: an arrangement for providing signals associated with arotational orientation of the core orientation device; processing meansfor processing the signals provided by the arrangement so as to provideprocessed data from which a measure of the rotational orientation of thecore orientation device can be established, the measure being associatedwith the rotational orientation of the device at a particular moment intime; memory for storing the processed data; and interface means havingfirst means for storing the processed data in the memory and secondmeans for accessing the memory to provide the measure of the rotationalorientation of core orientation device when required; wherein the coredrill comprises: means for maintaining knowledge of the relativerotational orientation of a core drilled by the core drill and the coreorientation device such that a measure of the rotational orientation ofthe core can be established using the measure of the rotationalorientation of the core orientation device.
 14. A core drill as claimedin claim 13 wherein the means for maintaining knowledge of the relativerotational orientation of the core drilled by the core drill comprises amechanism for preventing rotational movement about the length of thecore sample, relative to the core orientation device.
 15. A core drillas claimed in claim 13 including means for relating the measure of theorientation of the core orientation device with the present orientationthereof such that the core orientation device can be rotated to reflectthe measure of the orientation of the core orientation device.
 16. Acore drill as claimed in claim 13, wherein the core drill includes anouter tube assembly and an inner tube assembly with the inner tubeassembly having a means for accommodating the core orientation devicealong the length of the inner tube assembly.
 17. A core drill as claimedin claim 16 wherein the inner tube assembly includes a bearing allowingthe means for accommodating the core orientation device to rotaterelative to the outer tuber assembly but not relative to the core samplewhen the core is received by the inner tube assembly.
 18. A core drillas claimed in claim 16 wherein the core orientation device iscylindrical and one end of the core orientation device includes displayand input means in the form of a LCD display and keypad, the end of thecore orientation device being protected by the inner tube assembly whenaccommodated.
 19. A core drill as claimed in claim 16, wherein the outertube assembly includes a spacer for allowing the inner tube assembly tobe fitted with the outer tube assembly when the core orientation deviceis accommodated.
 20. A method of obtaining and orientating a core samplecomprising: moving a core drill having a core orientation device from afirst location to a drilling location and thereafter operating the coredrill to drill a core sample; generating signals associated with aphysical orientation of the core orientation device between the firstlocation and the drilling location; processing the signals to provideprocessed data from which a measure of orientation of the coreorientation device at the drilling location can be established; andstoring the processed data in memory such that the measure of thephysical orientation of the core orientation device can be obtainedtherefrom.